1. Field of the Invention
This invention relates to a lens unit and an image capturing apparatus, and particularly to a lens unit which collapses optical member in a bending optical system.
2. Background Technology
In recent years, as the use of personal computers has been increasing, there has also been widespread use of digital cameras for which images can be easily uploaded to personal computers. Also, digital cameras are now generally incorporated into information processing devices such as mobile computers, cellular phone, personal digital assistants (PDAs) and the like. As the use of these types of digital cameras has become more widespread, there has been increasing demand for more compact digital cameras, and thus there is need for the lens unit to be even smaller in size.
It has been proposed that the lens unit is made more compact by reducing the depth direction of the digital camera, such that even when the magnification is changed, the total length of the photographing lens unit is not changed (Patent Documents 1,2 and 3). In these documents, a bending member is provided on the optical path and after the optical path is bent by approximately 90 degrees, the optical images are formed on the image pickup device using the successive lens group.
However, in the three aforementioned documents, because lens are disposed closer to the object side than to the bending member, the length of the depth direction of the digital camera is limited by the length between the bending member and the object-side lens.
In order to solve this problem, a technique has been proposed in which the bending member is moved and the object side lens is retracted into the space that is created due to the movement of the bending member and thus the camera is compact when not in use (Patent Documents 4).
[Patent Document 1] Japanese Patent Application Laid-Open Publication No. 2000-131610
[Patent Document 2] U.S. Pat. No. 6,850,373B2
[Patent Document 3] US Patent Application No. 2003-16092A1
[Patent Document 4] Japanese Patent Application Laid-Open Publication No. 2003-169236
In the lens unit described in Patent Documents 4, a collapsible structure is disclosed in which when the object side lens is switched from the operating state to a non-operating state, the holding frame which holds the lens is supported by two holding shafts, and one of the shafts supports the lens such that it slides in the optical axis direction, and the other shaft supports the lens such that rotation in the optical axis direction is prevented at the time of sliding, and the lens frame is moved from the operating position to the storing position by driving the cam plate in the holding shaft vicinity.
However, in this structure, in the optical system which has a large interval between the bending member and the object side lens, or the high power zoom lens in which the object side lens is moved due to magnification change, the amount of movement of the lens associated with collapsing becomes large, and in the non-operating state it is difficult to reduce the depth direction of the digital camera, and the lens unit becomes large in size.
This invention was conceived in view of these problems and the object thereof is to provide in the bending optical lens, a compact lens unit in which the depth direction of the camera in the non-operating state is shortened even for an optical system in which the object side lens projects to a greater extent than the bending member and for a high power zoom lens in which the object side lens moves to a great extent.